RT Journal Article SR Electronic T1 Inhomogeneous Localization of Radioactivity in the Human Kidney After Injection of [111In-DTPA]Octreotide JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 1168 OP 1171 VO 45 IS 7 A1 de Jong, Marion A1 Valkema, Roelf A1 van Gameren, Arthur A1 van Boven, Hester A1 Bex, Axel A1 van de Weyer, Eric Pieter A1 Burggraaf, Jan Dirk A1 Körner, Meike A1 Reubi, Jean-Claude A1 Krenning, Eric P. YR 2004 UL http://jnm.snmjournals.org/content/45/7/1168.abstract AB In peptide receptor radionuclide therapy (PRRT) using somatostatin analogs labeled with β-emitters, the radiosensitive kidney is the dose-limiting organ, because of high uptake and retention of the radionuclides after glomerular filtration. Dosimetry calculations are mostly based on the MIRD scheme, assuming homogeneous renal radioactivity distribution. The aim of this study was to reveal the radioactivity distribution in the normal human kidney after intravenous injection of [111In-diethylenetriaminepentaacetic acid (DTPA)]octreotide. Methods: Three patients received intravenous injection of [111In-DTPA]octreotide before nephrectomy because of renal cancer. Distribution of radioactivity in the human kidney was investigated using SPECT scanning before and ex vivo autoradiography of the kidney after surgery. Results: Radioactivity was localized predominantly in the cortex of the kidney. In the cortex, radioactivity was not distributed homogeneously but formed a striped pattern, with most of the radioactivity centered in the inner cortical zone. Conclusion: These findings show that average dose calculations using the MIRD scheme, assuming homogeneous renal radioactivity distribution, are inadequate to estimate the radiation dose to various parts of the kidney after PRRT. Different effects due to inhomogeneity can be expected from PRRT using radionuclides emitting particles with short particle ranges, for example, Auger electron emitters, α-emitters, and low-energy β-emitters.